Sensor Sizes

Canon digital SLR cameras are available with 3 different sized sensors:

Full Frame: 36.0 mm by 24.0 mm
APS-H (1.3 crop) 27.9 mm by 18.6 mm
APS-C (1.6 crop) 22.2 mm by 14.8 mm

Note that these all have a 3:2 aspect ratio. Also note that each of these has been available in different pixel densities as manufacturing technologies have progressed. And also note that the 1.3 crop APS-H sensors may be a thing of the past.

Pixel density

I was curious about the actual size of the pixels on 4 specific cameras I own.

Canon 20D APS-C 8.2 Mpx 3,520 by 2,344 (6.3 micron pixels)
Canon 1Diii APS-H 10.1 Mpx 3,888 by 2,592 (7.17 micron pixels)
Canon 5Dii FF 21.1 Mpx 5,616 by 3,744 (6.41 micron pixels)
Panasonic LX3 10.1 Mpx 3776 by 2520 (2.1 micron pixels)

Interestingly the 20D and 5Dii pixels are very similar in size. The pixels on the 1D Mark III sensor are about 30 percent bigger in area, which accounts for its excellent high iso performance (for its time).

Also note that the 1Diii has light gathering "lenslets" over the sensor elements that give it light gathering capacity more like 8.4 microns. The same is almost surely true with the 5Dii.

The LX3 point and shoot allows a selection of 3 aspect ratios, the resolution quoted is for the 3:2. Not surprisingly it yields quite a lot of noise at ISO 400.

Note that the high pixel count of the 5Dii makes it unnecessary to "blow up" an image as much as would be needed for an image from a sensor with less pixels. As much as I like to downplay the "need" for more pixels, more pixels have undeniable advantages with respect to noise. Noise becomes more obnoxious the more an image is enlarged, and images from a sensor with lots of pixels just don't need to be enlarged as much.

Feedback? Questions? Drop me a line!

Tom's Photography Info / tom@mmto.org